Sounds fun, it might be worth looking into blueprints and having the modular pieces or buildings/wall sections instanced through there and potentially even procedural generate them for ease of placement and to prevent a repetitive look.
He could also create ‘prefabs’ bring in a load of modular pieces, build 5 or so different houses them combine them. See here (https://answers.unrealengine.com/questions/123763/combining-static-mesh-in-editor.html)
Then using a blueprint to place those prefabs?
Either way it sounds like you have the general gist, I personally would just have 2 UV’s 1 for texture 1 for lightmass and use vertex blending to add dirt and decals to have the finishing touch.